You strike (with "i", not "o") the keys of a piano, but you can also press them (implying a different amount of force and velocity).
Horns, cornets, and trumpets have valves, and you press or push down on them. Bugles are valveless (like a Post horn).
The Grove's Dictionary of Music and Musicians
will contain all of the terms, but not necessarily in a way that will do you a lot of good.
I would recommend a Visual Dictionary if you can find one. It's an organized collection of pictures that illustrate all sorts of things and have them labeled. Obviously it won't have everything, but I have the Macmillan Visual Dictionary
in the four-language version (English, French, German, Spanish) and find it very useful.
I just found the online Merriam-Webster Visual Dictionary here: http://visual.merriam-webster.com/
Here's the page for the parts of a trumpet: http://visual.merriam-webster.com/arts-archit...